The rotating disc electrode is one of the most sensitive tools known in aqueous electrochemistry. In this paper, the use of a rotating disc electrode in an investigation of the properties of a heavy metal fluoride melt at 600°C is described. The electrochemical response of trace amounts of transition metals such as Fe2+ and Ni2+ on a carbon electrode shows that the standard theory of the rotating disc fits well with the experimental data. Both the rotation speed dependence and the pulse amplitude dependence of the peak currents were found to be as predicted by the theory. The former showed a linear dependence of peak current on square root of rotation speed over the range from 50-2000 rpm. The peak current was found to be linear with increasing pulse amplitude up to 80 mV. The rotating disc was found to provide a much more reproducible response than earlier electrode constructions.